This invention relates to improvements in and relating to antimicrobial compositions. More particularly, it relates to antimicrobial compositions comprising or including a mixture of oils of melaleuca alternifolia and leptospermum scoparium and/or fractions/dilutions of same.
In recent years increased effort has been devoted to investigating and isolating commercially useful extracts from native plants and animals internationally. In some respects this has been motivated by continuing resistance developed by infective organisms and diseases to conventional therapies but also by a desire to extract full benefit from the world""s resources. In some cases the biological organism can be chemically active in its raw state, but more usually isolation or other treatment is necessitated to release the therapeutic and/or prophylactic effects. In New Zealand, essential oils have been extracted from New Zealand manuka tree (leptospermum scoparium) on a commercial basis for some years although the industry continues to grow. Manuka oil has been used to date in various applications including aromatherapy, cosmetics1 and as a toothpaste ingredient. According to one source2 manuka is the most abundant and widely distributed flowering native tree in New Zealand. It was historically used in New Zealand by Maori and later European settlers for purposes including the treatment of respiratory ailments, burns, dandruff, dysentery, fever, and indigestion, as well as being drunk as a type of tea. The biologically active ingredient is the oil accumulated in oil glands in the leaves. Whilst research3 indicates that there may be different chemotypes of manuka in New Zealand, the present invention relates to all New Zealand chemotypes, although particular reference is made to manuka derived from the East Cape region of New Zealand.
1Kennedy and Myleck (1998) A Downunder Perspective on Botanicals in Cosmetics, Botanicals in Cosmetics, Marcel Dekker Inc., Impress (1998) 
2Perry et al, Essential Oils from New Zealand Manuka and Kanuka: Chemotexonomy of Leptospermum, Phytochemistry 44(8): 1485 to 1495 (1997) 
3Perry et al 1997 as above 
Manuka, whilst colloquially known in New Zealand as xe2x80x9cthe tea treexe2x80x9d is a completely different species to the Australian tea tree (melaleuca alternifolia).
Given the prevalence of the manuka and Australian tea trees in their respective countries, together with a wish to further investigate the biological properties of these species, it would be desirable to identify and apply the biological properties in a commercially and biologically useful manner.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description, which is given by way of example only.
According to one aspect of the present invention there is provided a method of preparing a broad spectrum antimicrobial composition comprising combining the oils of leptospermum scoparium and melaleuca alternifolia. 
Use of the combination is clearly highly advantageous over use of the whole oils individually.
In addition to whole oils, active (that is, having microbial activity or activity against microbes) antimicrobial dilutions and/or fractions of same are within the scope of the present invention.
Conventional oil extraction methods are well known, and may be used to extract the oils, or fractions of same, from the two trees or species.
According to another aspect of the present invention there is provided a method of preparing an antimicrobial composition, substantially as described above, to have effect against a targeted microbe comprising altering the proportions of the constituent leptospermum scoparium or melaleuca alternifolia oils as appropriate to specifically target said targeted microbe.
The proportions of the respective oils may each range between 1-99%, by volume, but may preferably fall within the range of substantially 30-70% respectively depending on the targeted microbe. Each or both of the two oils may be present in xe2x80x9cincreasedxe2x80x9d or xe2x80x9clessorxe2x80x9d amounts, proportionally, depending on the targeted microbes.
According to another aspect of the present invention there is provided a method of preparing an antimicrobial composition, substantially as described above, for having effect against gram negative microbes by increasing the proportion of melaleuca alternifolia in the composition.
According to another aspect of the present invention there is provided a method of preparing an antimicrobial composition, substantially as described above, for having effect against gram positive microbes by increasing the proportion of leptospermum scoparium oil in the composition.
According to another aspect of the present invention there is provided a method of increasing the potency of the broad-spectrum antimicrobial composition, substantially as described above, comprising the step of extracting high potency fractions of the oils and incorporating them into the composition.
The high potency fractions may be used in whole or diluted form and in combination or singly.
According to further aspects of the present invention there is provided broad spectrum antimicrobial compositions, produced according to the above methods.
According to a further aspect of the present invention there is provided an antimicrobial composition substantially as described above, containing a fraction of melaleuca alternifolia oil having high potency, as defined hereinafter.
According to a further aspect of the present invention there is provided an antimicrobial composition substantially as described above comprising predominantly enhanced terpinen-4-ol.
According to a further aspect of the present invention there is provided an antimicrobial composition containing a fraction of melaleuca alternifolia oil having lower potency, as defined hereinafter.
According to a further aspect of the present invention there is provided an antimicrobial composition substantially as described above comprising predominantly compounds selected from one or more of the following group: pinenes, myrcene, 2-carene, limonene, gamma terpinen and lower levels of Terpinen-4-ol.
According to a further aspect of the present invention there is provided an antimicrobial composition, containing a fraction of leptospermum scoparium having high potency, as defined hereinafter.
According to a further aspect of the present invention there is provided an antimicrobial composition substantially as described above comprising predominantly enhanced levels of flavesone, isoleptospermone and leptospermone.
According to another aspect of the present invention there is provided an antimicrobial composition containing a fraction of leptospermum scoparium having lower potency, as defined hereinafter.
According to a further aspect of the present invention there is provided an antimicrobial composition substantially as described above comprising predominantly lower levels of monoterpines and/or lower concentrations of flavesone, isoleptospermone and leptospermone.
Combinations and dilutions of the above whole oils, fractions or dilutions thereof and/or combinations thereof are also within the scope of the present invention given the hitherto unknown finding that the said combinations provide a novel and effective broad spectrum antimicrobial composition.
Applications of same including those relating to antimicrobial treatments in general together with those relating to the treatment or prevention of minor microbial related ailments or conditions in humans are also within the scope of the present invention.